In this project it is intended to evaluate the conformations of reduced alkylated and plasmin-modified derivatives of human chorionic somatomammotropin (HCS or HPL) by fluorescence and circular dichroism measurements. The contribution of the carboxy-terminal disulfide to the total optical activity of HCS will be determined. The reduction and alkylation of plasmin modified HCS will be studied and the conformations and biological activities of purified fragments will be evaluated. Complementation of these fragments with natural and synthetic fragments from various pituitary growth hormones will be tried and the products evaluated as to conformation and biological activity. The conformational stability of all derivatives and products will be evaluated by thermal denaturation. These results will be correlated with biological and immunochemical potencies of the materials. BIBLIOGRAPHIC REFERENCES: Rao, A.J., Ramachandran, J., and Li, C.H. Human pituitary growth hormone. 44. Effects of plasmin-modified hormone and its fragments on ornithine decarboxylase activity and lipolysis. Proc. Soc. Exp. Biol. Med. 151, 285-287 (1976). Bennett, L.L., Curry, D.L., and Li., C.H. Enhancement of insulin secretion by human chorionic somatomammotropin and related hormones. Proc. Soc. Exper. Biol. Med. 152, 281-283 (1976).